Display problem

[beekerc]

i have a water damaged iphone 6s. both of the water contact indicators are red.

i put in a good battery and a known good LCD screen, no activity.
i have tested the screen that came with it on a different (good) phone and the button, digitizer and display all work fine.
i was able to get the (bad) phone into both Restore and DFU mode and have updated the IOS to 14.1 - without the screen attached.
i have also given the mobo a gentle wash (99% IPA) and scrub (soft child's toothbrush) and let it dry in a very warm room for 3 days.

so here’s the problem. the mobo seems to work well enough - boot, update IOS, talk with itunes - but there’s no visual activity, even with a known good LCD screen.

the connectors for the LCD are part of the motherboard, so i’m thinking that while the motherboard is mostly good, there’s probably some visual circuitry that has been compromised. is there any way to troubleshoot this further? or is the mobo (and phone) pretty much a write-off?

i can do component level swaps in iphones, but i don't have the ability to micro-soldering or chip replacements.

thanks in advance for any advice
B

 

[BugeyeSTI]

Sounds like board level repair is necessary to fix the phone. Honestly the 6S is worth $100-$125 in good condition so a repair isn't worth the hassle in my opinion. You might be able to sell it as a parts phone but as it has water damage it probably wouldn't fetch much

 

[beekerc]

@BugeyeSTI
yeah i hear you. if you're convinced it's a board level repair, it'll probably become my battery charger - live mobo in an open back case that i can drop a battery into. it still talks to 3utools so i can get a battery health read.
was really hoping there might be a way to get the video circuit working again.
Thanks

 

[Lekro]

Check if it's only the backlight gone out or the entire LCD. Shine a bright light while the screen should be on.

If you can see the pixels without backlight, it is still a board level issue but at least the repair is straight forward and a routine procedure for decent repair sites.

 

[beekerc]

@Lekro
is backlight a function of the lcd screen assembly or of the motherboard.

 

[Lekro]

The part I’m talking about is a circuit on the motherboard.